The invention has as an object a receptacle for foods and means for triggering a chemical reaction for the production of integral heat.
There presently exists a number of receptacles which are self heating. Those receptacles have a number of drawbacks. For example, it is difficult to stock those receptacles for a long time. The reactive products, if not packaged in an effectual manner become inoperative with time, generally after fifty or sixty days. The methods utilized for creating the chemical reaction which produces the heat for warming the foods are more or less effectual.
Generally, in the embodiments of the prior art there are a number of pouches of reactive product, for example calcium oxide or quick lime, or potassium hydroxide and ortho-phosphoric acid or an oxide of calcium or quick lime and a pouch of water. Means are provided to puncture the pouches to permit the reactions. Those pouches are disposed inside an upper part so that it provides a fast exothermic reaction which is rapid but often times limited because of improper mixture between the water and the reactive chemicals.
There are a number of patents which describe self heating receptacles. However, the embodiments described in the prior art have a number of drawbacks, including incomplete reaction of the quick lime and the likelihood of untimely or accidental triggering of the reaction, which can be dangerous. The present invention improves the method by which the reaction is triggered, thereby enhancing the security of the receptacles and assuring a good reaction of all of the quick lime.
The German Pat. No. 1,214,600 discloses a well-defined mixture of fruit juices and milk, and consequently does not show the use of a reactive mixture.
The device disclosed in U.S. Pat. No. 3,085,681 cannot be used for the uses contemplated by the present invention because of the risks associated with that device. There the water is necessarily contained inside an interior pocket, the quick lime cannot be absolutely saturated by the water because of the disposition of two envelopes--thereby providing an incomplete reaction of the quick lime. Additionally, the interior pocket can explode under the pressure of the vapor given off by the quick lime at the moment of reaction; alternatively, the vapor will remain trapped and consequently will not heat in some cases the foods in a third container.
U.S. Pat. No. 3,871,357 in the plane of opening of the pouch of water only opens just one time out of three or four, because the pouch is free and so are the cutting projections. In commercial applications, as well as in the patent, the risks associated with this embodiment of the prior art are great, for example, a closing plate on the projections can, if the foods are heavy, cut the vessel that holds them, or burst, when the projections are engaged in an arrested position, and even though it may have little liquid, the reaction will be triggered immediately. When stirring the vessel the pouch of water can break open when it hits the point of projections, thereby uncontrollably triggering a reaction.
In French Pat. No. 2,348,121, an adhesive band is provided to hermetically seal a pouch of water. The problem is that as a result of humidity, very high heat, or low temperatures, the adhesive band can be detached, setting off a reaction that would then be uncontrollable. In this French patent, the pouch of water is fastened at an extremity and a cord, independent of the pouch, is disposed in another extremity, that permits a certain movement to the interior of the heating vessel, thereby creating a risk of laceration and of uncontrollable reaction of the reactive chemicals during stocking, transportation or transshipment.
A Swiss process, under the name Pozell, Blanchat, Bertrand, is commercially available and in conception is substantially identical with respect to assembly of the vessels, to the assemblies as described in U.S. Pat. No. 2,871,357 and of the previously recited German and American patents, and French Pat. No. 2,348,121 which depends upon the opening of a pouch of water. The latter is fastened by one extremity to a small cardboard plate as well as the opening cord which, independently of the pouch, is also secured at one end to the cardboard. All the elements can be displaced freely, and without anchoring to the heating vessel--thereby raising the constant danger that the fastenings could perhaps cut or lacerate the vessels carrying the foods. In that event the liquids contained in the food vessel can set off the reaction. The same thing can happen if the heating vessel and the water pouch are pierced which can provoke the chemical reaction at an inopportune moment.
It should also be noted that in all of the above cited references, the quick lime is loose in the interior of the heating vessel--inviting a malfunction such as lack of total reaction, or localized reaction in the vessel, which, therefore, will not permit the perfect heating of the food contained in the upper vessel, or very often, the heating of only one part.
Also, the existing receptacles have a flat water pouch covered almost totally by the heating surface, thus providing a screen for the diffusion of heat to the upper part of the receptacle which contains the food..